This idiom comes from the Tang dynasty poem
登鹳雀楼 (Ascending Stork Tower) by
王之涣 (Wáng Zhīhuàn). The full couplet reads:
欲穷千里目,
更上一层楼 — 'To see a thousand miles further, climb one more story of the tower.' The poem is one of the most memorized in the Chinese classical canon.